In reply to Martin W:
> Pretty much all chat shows on all channels have 'guests' who are mainly there to plug their latest film/book/stage show/tv show. Jonathan Ross and Graeme Norton would be the obvious examples. The guests don't go on the shows because they like the host, it's all part of the product launch publicity cycle.
Indeed sometimes the whole show appears to only be there to promote a specific film. Graeme Norton seems particularly bad for this, I saw a few minutes of one of his shows recently where the entirety of his guests appeared to be the four leads from the new Ghostbusters film.